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  1. I

    230V AC to 12V DC @90 AMP

    I can't quite agree with the "over simplification" of the transformer in terms of how much DC current will flow. If the primary is switched at such a frequency that the core never saturates, there is no DC current. The primary current waveform is the familiar ramp on a step (trapezoidal). The...
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    Op amp theory Q's

    I'm no expert when it comes to audio, but I do know a bit about op-amps. Audio is a very personal thing.... somethings sounds good to one person, while the next person thinks it sounds bad/flawed. Whenever I buy audio gear, I go into the sound room, close my eyes, and tell the salesman to...
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    Need Help(I hv a bulb,need it to glow)

    What aspect of aviation
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    frequency and voltage in DC motor

    By definition, a Root Mean Square (RMS) voltage gives the same heating effect as a DC voltage of the same value. In the case of a square wave, the RMS value is: Vrms=Vpk*Sqrt(Ton/period) Ton/period is also the duty cycle.
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    230V AC to 12V DC @90 AMP

    What your trying to do is possible, but not easy. The transformer type is unimportant as long as you remain within its limitations. Oh..... I forgot to mention, what your trying to build here is formally called a single ended forward converter. Since I don't see any active reset circuitry for...
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    frequency and voltage in DC motor

    75% duty cycle is 75% duty cycle and frequency has nothing to do with what the voltage will be. The average voltage will be the duty cycle multiplied by the input voltage. Motors are wound such that they have pole pairs. I have seen up to a 12 pole DC motor. The easy way to find out how many...
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    Transformer and LM317 Question

    Like many 3 terminal regulators, there is a reference voltage between the output pin and the adjust pin. In the case of the LM317, it's 1.25V
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    Transformer and LM317 Question

    Ahhhhh yes....... I should have checked the data sheet first. Yup, since the reference voltage is between the output pin and adjust pin (not adj pin to common... I guess I've been around TL431's too long), any resistance in series will screw up the load regulation (not line regulation). As for...
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    Transformer and LM317 Question

    The .22 ohm resistor does not ruin the LM317's voltage regulation. D5 is another story as far as regulation... it's forward voltage will change with current and temperature. The point that is regulated is the "node" from which the feedback is taken. In this case the "output" side of the .22 ohm...
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    +- power supplies

    A power supplies output is only the voltage potential between the terminals. It's polarity is determined by which terminal is used as the reference.
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    Best circuit drawing software out there?

    The company I work for recently dumped PCAD in favor of PADS....  I liked both, but prefer PADS. I suppose it's what your use too. I did find it easier to make "intelegent" schematics in PADS when linking to the layout. As for simulators... Orcad, MicroSim, Intusoft and Workbench. My vote goes...
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    Need help w/full wave bridge rectifier

    I don't think it would be a wise thing to take a 180-200VAC signal, rectify it and try to charge a battery without a regulator!!! The batteries internal resistance is probably what's holding the voltage down. As for the diode voltage rating.... you are interested in something called PVI (peak...
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    switch mode power supply

    Can you be a little more specific about your problem, and describe the power supply further? In general, switching power supplies take a DC voltage and "chop-it" into a square wave. In the case of an off-line switcher, the AC is rectified, filtered and then "chopped". In a DC-DC it is just...
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    op-amp low frequency pulse generator

    First, let me reiterate that the concept I am referring to, is applicable to transient circuit analysis (not steady-state), and by definition only holds true for the instant in time that you are interested. Again, take a simple series RC circuit with a source and switch. To make it simple, let
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    op-amp low frequency pulse generator

    Mr Klampfer Explain to me what you don't understand about the following statement? "While applying principals of transient circuit analyisis, capacitors become "SHORTS" with a series voltage source and inductors become "OPENS" with a parallel current source. "
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    Help Needed Calculating Resistance

    14mA thru 5K is 70V. Is that what you meant to say??
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    op-amp low frequency pulse generator

    "Of course the capacitor's voltage is at ground the moment power is applied to the circuit...." That's not the point.... you said, "You were taught wrong." He wasn't, and I just gave a simple example of how a capacitor can "appear" to look like a "SHORT" (short being the key word) to ground...
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    op-amp low frequency pulse generator

    He wasn't "exactly" taught wrong, you just have to remember the conditions under which it is true!! Take a simple series RC circuit (no initial conditions i.e. 0 volts on the cap)with a DC source and a switch. If you close the switch at time "zero" the capacitor at that instant indeed looks like...
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    Which one of these is correct!? (State technique for an electrical network)

    From what I remember, and that was close to 30 years ago, it's just like writing mesh equations..... if you use the same conventions everywhere, the worst that can happen is the result, relative to your chosen polarity/direction will be negative.
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    op-amp low frequency pulse generator

    Without going into the differential equations, the solution and general form for charging is: Vcap=Vapplied*(1-e^-t/RC) and for discharge is: V=Vcap*(e^-t/RC) on the discharge, don't forget to include the forward voltage of the diode.
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